Archive for ISBA

To Susie [by Kerrie Mengersen]

Posted in pictures, Statistics, University life with tags , , , , , , , on August 21, 2014 by xi'an

[Here is a poem written by my friend Kerrie for the last ISBA cabaret in Cancun, to Susie who could not make it to a Valencia meeting for the first time... Along with a picture of Susie, Alicia and Jennifer taking part in another ISBA cabaret in Knossos, Crete, in 2000.]

This is a parody of a classic Australian bush poem, ‘The Man from Snowy River’, that talks of an amazing horseman in the rugged mountain bush of Australia, who out-performed the ‘cracks’ and became a legend. That’s how I think of Susie, so this very bad poem comes with a big thanks for being such an inspiration, a great colleague and a good friend.

There was movement in the stats world as the emails caught alight
For the cult from Reverend Bayes had got away
And had joined the ‘ISBA’ forces, and were calling for a fight
So all the cracks had gathered to the fray.

All the noted statisticians from the countries near and far
Had flown into Cancun overnight
For the Bayesians love their meetings where the sandy beaches are
And the Fishers snuffed the battle with delight.

There were Jim and Ed and Robert, who were ‘fathers of the Bayes’
They were known as the whiskey drinking crowd
But they’d invented all the theory in those Valencia days
Yes, they were smart, but oh boy were they loud!

And Jose M Bernardo came down to lend a hand
A finer Bayesian never wrote a prior
And Mike West, Duke of Bayesians, also joined the band
And brought down all the graduates he could hire

Sonia and Maria strapped their laptops to the cause
And Anto, Chris and Peter ran – in thongs!
Sirs Adrian and David came with armour and a horse
While Brad and Gareth murdered battle songs

And one was there, a Spaniard, blonde and fierce and proud
With a passion for statistics and for fun
She’d been there with the founders of the nouveau Bayesian crowd
And kept those Fisher stats folk on the run

But Jim’s subjective prior made him doubt her power to fight
Mike Goldstein said, ‘That girl will never do,
In the heat of battle, deary, you just don’t have the might
This stoush will be too rough for such as you.’

 But Berger and Bernardo came to Susie’s side
We think we ought to let her in, they said
For we warrant she’ll be with us when the blood has fairly dried
For Susie is Valencia born and bred.

She did her Bayesian training in the classic Spanish way
Where the stats is twice as hard and twice as rough
And she knows nonparametrics, which is useful in a fray
She’s soft outside, but inside, man she’s tough!

She went. They found those Fisher stats folk sunning on the beach
And as they grabbed their laptops from the sand
Jim Berger muttered fiercely, ‘right, twist any head you reach
We cannot let those Fish get out of hand.’

Alicia, grab a Dirichlet and break them with a stick
Chris, it’s easy, just like ABC
And Sylvia, a mixture model ought to do the trick
But just you leave that Ronnie up to me.

Jose battled them with inference and curdled Neyman’s blood
And Ed told jokes that made them shake their head
And posteriors lined like beaches like sandbags for a flood
And Jim threw whiskey bottles as they fled.

And when the Bayesians and the Fishers were washed up on the sand
The fight was almost judged to be a tie
But it was Susie who kept going, who led the final charge
For she didn’t want objective Bayes to die

She sent the beach on fire as she galloped through the fray
Hurling P and F tests through the foam
‘til the Fishers raised surrender and called the fight a day
And shut their laptops down and sailed for home.

And now at ISBA meetings where the Bayesians spend their days
To laugh and learn and share a drink or two
A glass is always toasted: to Susie, Queen of Bayes
And the cheering echoes loudly round the crew.

She will be remembered for setting Bayesian stats on fire
For her contributions to the field are long
And her passion and her laughter will continue to inspire
The Bayesian from Valencia lives on!

hasta luego, Susie!

Posted in Statistics, University life with tags , , , , , , , , on August 20, 2014 by xi'an

I just heard that our dear, dear friend Susie Bayarri passed away early this morning, on August 19, in Valencià, Spain… I had known Susie for many, many years, our first meeting being in Purdue in 1987, and we shared many, many great times during simultaneous visits to Purdue University and Cornell University in the 1990’s. During a workshop in Cornell organised by George Casella (to become the unforgettable Camp Casella!), we shared a flat together and our common breakfasts led her to make fun of my abnormal consumption of cereals  forever after, a recurrent joke each time we met! Another time, we were coming from the movie theatre in Lafayette in Susie’ s car when we got stopped for going through a red light. Although she tried very hard, her humour and Spanish verve were for once insufficient to convince her interlocutor.

Susie was a great Bayesian, contributing to the foundations of Bayesian testing in her numerous papers and through the direction of deep PhD theses in Valencia. As well as to queuing systems and computer models. She was also incredibly active in ISBA, from the very start of the Bayesian society, and was one of the first ISBA presidents. She also definitely contributed to the Objective Bayes section of ISBA, especially in the construction of the O’Bayes meetings. She gave a great tutorial on Bayes factors at the last O’Bayes conference in Duke last December, full of jokes and passion, despite being already weak from her cancer…

So, hasta luego, Susie!, from all your friends. I know we shared the same attitude about our Catholic education and our first names heavily laden with religious meaning, but I’d still like to believe that your rich and contagious laugh now resonates throughout the cosmos. So, hasta luego, Susie, and un abrazo to all of us missing her.

Cancún, ISBA 2014 [day #3]

Posted in pictures, Statistics, Travel, University life with tags , , , , , on July 23, 2014 by xi'an

Cancun13…already Thursday, our [early] departure day!, with an nth (!) non-parametric session that saw [the newly elected ISBA Fellow!] Judith Rousseau present an ongoing work with Chris Holmes on the convergence or non-convergence conditions for a Bayes factor of a non-parametric hypothesis against another non-parametric. I wondered at the applicability of this test as the selection criterion in ABC settings, even though having an iid sample to start with is a rather strong requirement.

Switching between a scalable computation session with Alex Beskos, who talked about adaptive Langevin algorithms for differential equations, and a non-local prior session, with David Rossell presenting a smoother way to handle point masses in order to accommodate frequentist coverage. Something we definitely need to discuss the next time I am in Warwick! Although this made me alas miss both the first talk of the non-local session by Shane Jensen  the final talk of the scalable session by Doug Vandewrken where I happened to be quoted (!) for my warning about discretising Markov chains into non-Markov processes. In the 1998 JASA paper with Chantal Guihenneuc.

After a farewell meal of ceviche with friends in the sweltering humidity of a local restaurant, I attended [the newly elected ISBA Fellow!] Maria Vanucci’s talk on her deeply involved modelling of fMRI. The last talk before the airport shuttle was François Caron’s description of a joint work with Emily Fox on a sparser modelling of networks, along with an auxiliary variable approach that allowed for parallelisation of a Gibbs sampler. François mentioned an earlier alternative found in machine learning where all components of a vector are updated simultaneously conditional on the previous avatar of the other components, e.g. simulating (x’,y’) from π(x’|y) π(y’|x) which does not produce a convergent Markov chain. At least not convergent to the right stationary. However, running a quick [in-flight] check on a 2-d normal target did not show any divergent feature, when compared with the regular Gibbs sampler. I thus wonder at what can be said about the resulting target or which conditions are need for divergence. A few scribbles later, I realised that the 2-d case was the exception, namely that the stationary distribution of the chain is the product of the marginal. However, running a 3-d example with an auto-exponential distribution in the taxi back home, I still could not spot a difference in the outcome.

Cancún, ISBA 2014 [day #0]

Posted in Statistics, Travel, University life with tags , , , , , , , , on July 17, 2014 by xi'an

Day zero at ISBA 2014! The relentless heat outside (making running an ordeal, even at 5:30am…) made the (air-conditioned) conference centre the more attractive. Jean-Michel Marin and I had a great morning teaching our ABC short course and we do hope the ABC class audience had one as well. Teaching in pair is much more enjoyable than single as we can interact with one another as well as the audience. And realising unsuspected difficulties with the material is much easier this way, as the (mostly) passive instructor can spot the class’ reactions. This reminded me of the course we taught together in Oulu, northern Finland, in 2004 and that ended as the Bayesian Core. We did not cover the entire material we have prepared for this short course, but I think the pace was the right one. (Just tell me otherwise if you were there!) This was also the only time I had given a course wearing sunglasses, thanks to yesterday’s incident!

Waiting for a Spanish speaking friend to kindly drive with me downtown Cancún to check whether or not an optician could make me new prescription glasses, I attended Jim Berger’s foundational lecture on frequentist properties of Bayesian procedures but could only listen as the slides were impossible for me to read, with or without glasses. The partial overlap with the Varanasi lecture helped. I alas had to skip both Gareth Roberts’ and Sylvia Früwirth-Schnatter’s lectures, apologies to both of them!, but the reward was to get a new pair of prescription glasses within a few hours. Perfectly suited to my vision! And to get back just in time to read slides during Peter Müller’s lecture from the back row! Thanks to my friend Sophie for her negotiating skills! Actually, I am still amazed at getting glasses that quickly, given the time it would have taken in, e.g., France. All set for another 15 years with the same pair?! Only if I do not go swimming with them in anything but a quiet swimming pool!

The starting dinner happened to coincide with the (second) ISBA Fellow Award ceremony. Jim acted as the grand master of ceremony and he did great to add life and side stories to the written nominations for each and everyone of the new Fellows. The Fellowships honoured Bayesian statisticians who had contributed to the field as researchers and to the society since its creation. I thus feel very honoured (and absolutely undeserving) to be included in this prestigious list, along with many friends.  (But would have loved to see two more former ISBA presidents included, esp. for their massive contribution to Bayesian theory and methodology…) And also glad to wear regular glasses instead of my morning sunglasses.

[My Internet connection during the meeting being abysmally poor, the posts will appear with some major delay! In particular, I cannot include new pictures at times I get a connection... Hence a picture of northern Finland instead of Cancún at the top of this post!]

no ISBA 2016 in Banff…

Posted in Mountains, pictures, Statistics, Travel, University life with tags , , , , , , , , , , , , on July 13, 2014 by xi'an

Banff west-northern range from Rundle, Sept. 10, 2010Alas, thrice alas, the bid we made right after the Banff workshop with Scott Schmidler, and Steve Scott for holding the next World ISBA Conference in 2016 in Banff, Canada was unsuccessful. This is a sad and unforeseen item of news as we thought Banff had a heap of enticing features as a dream location for the next meeting… Although I cannot reveal the location of the winner, I can mention it is much more traditional (in the sense of the Valencia meetings), i.e. much more mare than monti… Since it is in addition organised by friends and in a country I love, I do not feel particularly aggravated. Especially when considering we will not have to organise anything then!

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